Pencil sharpener



Nov. 7, 1939. E. 1.. THEOBALD PENCIL SHARPENER Filed June 15, 1938 2Shets-Sheet 1 11W NTOR. wufv 4.

flax 6W ATTORNEY Nov. 7, 1939. 1 THEQBALD 2.179.140

PENCIL SHARPENER Filed June 15, 1938 2 Sheets-Sheet 2 N VEN TOR.

ATTORNEY Patented Nov. 7, 1939 PENCEL SHARPENER Edgar L. Theobald,Oakland, Calif. Application June 15, 1938, Serial No. 213,779

11 Claims.

This invention relates to a pencil sharpener.

The object of the present invention is generally to improve theconstruction and operation and to augment the functions of pencilsharpeners; to provide a mechanical device which is capable of handlingpencils of all types and diameters such as refill-pencils, wood orpapercovered pencils, colored pencils, etc.; to provide a pencilsharpener which will produce either a chisel point or theccnventionalround sharpened 'point; to provide a. pencil sharpener thatis motor driven and totally enclosed to catch and temporarily retain thegraphite dust, wood or other material removed from pencils during thesharpening operation; to provide a pencil sharpener employing motordriven high-speed discs constructed of or covered with an abrasivematerial; to employ discs of this character which are arranged singly orin pairs and whichpresent beveled opposed abrasive surfaces betweenwhich the end or point of the pencil to be sharpened is introduced; toprovide a mounting and drive for discs of this character which permitsthe discs when arranged singly or in pairs to be driven in the samedirection; to provide abrasive discs or a combination of discs which areindividually driven; to provide individual mount- I ings for theabrasive discs which permit movement of the discs to and away from eachother; and further, to provide a magnetic pullto yieldingly resistseparation of the discs and to return them to a normal position towardsthe end of eachoperation, a movement that may be augmented-by springmeans provided at the outer ends of both shafts' The pencil sharpener isshown by way of illustration in the accompanying drawings in which-.Fig. 1 is a central vertical longitudinal section of the pencilsharpener; I 1

Fig. 2 isacross-section taken on line I III of Fig. 1;

r Fig. 3 is a horizontal section of the motor F and a portion of thehousing enclosing the same;

Fig. 4 is a plan View of the pencil sharpener; and.

Fig. 5 is a wiring diagram showing the manner in which the switch, theplug connection and the reception of a drawer t and above the drawersufficient space for a series of grinding or cutting discs. The bracketsalso form asupportfor a pair of electric motors E and F which aresecured to the brackets by bolts 5. The bolts extend completely throughthe motors and the end plates C and D, and as such, first serve thefunction of securing the motors to the brackets, and secondly, that ofsecuring the end plates and the housing to the base.

Secured by set screws or other means on the inner end of each rotorshaft are hub members 6 and 6a, and secured thereto or formed integraltherewith are discs 7 andla which are covered with an abrasive materialsuch as carbide .bf silicon, carborundum, aluminum oxide or the like,cemented to cloth or leather. The'adjacent faces of the discs I and laare beveled or flared away from each other as shownin Fig. l, and

the angle formed between the flaring faces may be varied to the degreeof taper desired on a pencil point. One of the hubs is externallythreaded as shown at 8 to receive and secure the hub of a third disc 9.-Flaring facesof a somewhat smaller angle are formed between this discand the adjacent disc 7, and these faces are also coveredwith anabrasive which is intended for the purpose of sharpening leads ofrefillpencils and the like. Afourth disc i0 is secured to the hub 6a.This disc may be constructed of steel, and the face la is provided withradially disposed cutting teeth for the purpose of sharpening certaincolored pencils containing a parafiine base. However, the face llla may,if desired, be covered with a coarse abrasive, as thiswill accomplishsubstantially the same results.

By referring to Fig. 2, it will be noted that two openings l2 and M areformed in the housing, and that said openings align with the spaceformed between the discs l and la. The opening i2 is of a size toreceive pencils of standard diameter. The second opening I4 is providedto accommodate pencils of slightly larger diameter. Openings l5 and i6are also provided, the opening' it registering with the space formedbetween the discs '8 and 9-for the sharpening of refillpencils, and theopening it with the face ma. which is provided with cutting teeth or acoarser abrasive, preferably for sharpening colored pencils. The severalopenings just referred to may be radially disposed with relation to thecenters of the discs or they may be slightly offset to As all kinds ofindividuals are liable to operate machines of this character, suchindividuals might be referred to as skilled and unskilled, an unskilledperson being one who has had no experience with the operation of this orsimilar grinding machines. Such an unskilled person, when inserting apencil, is liable to force it inwardly between the discs more rapidlythan the wood and graphite are being cut away, and it is accordinglyessential that the discs should separate with relation to each otherwhen subjected to such conditions, as there would otherwise be atendency to overload and stall the motors whereby the discs are driven,which would stop all operation. In the present instance, motors of theinduction type are employed. The rotors l8 and I9 which drive the shaftsI8a and iSa are arranged out of center with respect to their stators andnormally tend to align themselves in the magnetic field produced by thestators 20 and 2|, but when a pencil is inserted between the discs I andla and tends to force them apart or away from each other, the rotors andthe shafts upon which they are mounted will move longitudinally in thebearings 30 and 40 and outwardly with relation to the stators 20 and 2!.Such movement is, however, magnetically resisted; hence, there is ayielding resistance to a separation of the discs 1 and la, but thisresistance is most desirable under the circumstances previouslydescribed, and upon it depends the smooth operation of the machine, asit greatly assists in preventing the overloading of the motors, and asit provides just the right amount of a yielding working pressure forbest operating results.

In addition to the magnetic resistance, the outer ends of the shaftsl8a. and I911 are rounded or provided with thrust ball bearings 24 whichengage plates 25 placed in each end of the housing. Behind these platesare blocks of sponge rubber 26 or the like, said blocks of sponge rubberand the plates 25 being mounted in cap bearings 21 which are screwedinto the opposite end plates D and C. These may be screwed inwardly oroutwardly and as such may place any end thrust desired on the rotorshafts. Hence when the abrasive discs and 1a are subjected to forceswhich tend to separate them, such forces are resisted, not only by themagnetic pull exerted by the concerted action of the rotors and thestators of the respective motors, but also by the compression action ofthe rubber blocks 26. The two thrust bearings described also provide adesirable means of aligning the abrasive discs in regard to theirrespective openings and furthermore exert a cushioning effect should anylongitudinal oscillations develop in the shafts. v

When referring to Fig. 1 it will be noted that a V-shaped deflector 28is placed centrally of the drawer 4, that is, midway between its ends.This deflector extends from end to end of the drawer and, by utilizingthe air current coming from the V-shaped opening between the high-speeddiscs, it serves the purpose of deflecting dust, wood and other materialremoved during the sharpening operation, causing said material to bethrown into opposite sides of the drawer, thereby preventing it frompiling up or building up around the abrasive or cutting discs.

The drawer is provided with .a knob 28a, and by exerting a pull, thedrawer may be removed through an opening in one side of the housing (seeFig. 2) and the dust and other foreign permit the abrasive to cut with ashearing action.

matter collected may thus be removed from time to time.

For the purpose of convenience, a cord connector 35 is placed in one endof the housing so that a plug such as shown at 36 may be plugged in andthe pencil sharpener connected to any available electric system. Aswitch 31 is similarly placed in the opposite end of the housing to makeor break the circuit through the motors.

Due to the fact that pencils produced by different manufacturers varyslightly in diameter, it is desirable to provide some of the openingsindicated at M, I5 and I6 with adjustable sleeves to take care of suchvariations. The sleeves are best illustrated at M in Figs. 1 and 2. Theupper and lower ends of the sleeves are provided with exterior taperingshoulders 42 and 43 which are engaged by internally tapered upper andlower bush-.

ing members 44 and 45. These bushings are screwed into the housing, andas the sleeves are longitudinally slotted at a plurality of points andfrom opposite ends, movement of the bushings by rotation thereof willcause the internal portions to engage the external tapered ends of thebushings and thereby cause contraction of the same, such contractionmaking it possible to adjust the sleeves to snugly fit pencils ofvarying diameters. Such adjustment retains the pencils against play orwobble when inserted through the openings, and at the same time retainsthe pencils in a position which is central between the abrasive discs,thereby assuring a perfect point, whether the point is round orchisel-shaped.

The opening it, as previously stated, aligns with the cutting face 10a.This face isparticu-a larly intended for cutting heavy wood orpapercovered pencils, colored pencils containing paraii'ine, and thelike. The opposed faces I and la may vary with respect to the grade ofabrasive material employed; for instance, one face may u ple andsubstantial in construction. Everything is arranged for rapidmanipulation and for the convenience of the operator. Compactness and abalanced symmetrical design are made possible by the use of two motors,while also simplifies the general construction and makes it possible toemploy the magnetic pull of the stators to resist separation of theabrasive discs. A single motor having the same horsepower as the twosmall motors now employed could obviously be used, but that wouldmaterially increase the height and width of the housing, and unbalancethe design due to the great diiference in weight between'the motor onone end and the abrasive equipment on the other end. It wouldfurthermore complicate the structure and the mechanism as the abrasiveThe necessary joining ofseveral Wires is done on the bottom face side ofthe base plate, thus avoiding any possibility of arcing or sparking dueto loose wire connections, etc. This is important, as'the graphite andwood dust represent a highly explosive material.

Having thus described my invention, what I claim and desire to secure byLetters Patent is: l. A pencil sharpener comprising a housing, a pair ofmotors enclosed by the housing, a pair of abrasive discs, each discindependently driven by a motor, said discs being closely spaced buthaving their adjacent faces beveled away from each other, with thegreatest spacing between their peripheral edges, to form a taperingpencil point, an opening formed in the housing to permit a pencil to beinserted between the opposed beveled discs, said discs being movable toand away from each other to permit separation when a pencil is insertedbetween the discs, and magnetic means resisting separation of the discsand restoring the discs to normal position when a pencil is removed.

2. A pencil sharpener comprising a housing, a pair of motors enclosed bythe housing, a rotor and shaft in each motor and having a limitedlongitudinal movement therein, a pair of abrasive discs, each discindependently driven by its rotor and shaft, said discs being closelyspaced but having their adjacent faces beveled away from each other,with the greatest spacing between their peripheral edges, to form atapering pencil point, an opening formed in the housing to permit apencil to be inserted between the opposed beveled discs, said discs,rotors and shafts being movable to and away from each other to permitseparation when a pencil is inserted between the discs, and means forresisting separation of the discs, rotors and shafts and restoring thediscs to normal position when a pencil is removed.

3. A pencil sharpener comprising a housing, a pair of motors enclosed bythe housing, a pair of abrasive discs, each disc independently driven bya motor, said discs being closely spaced but having their adjacent facesbeveled away from each other, with the greatest spacing between theirperipheral edges, to form a tapering pencil point, an opening formed inthe housing to permit a pencil to be inserted between the opposedbeveled discs, said discs being movable to and away from each other topermit separation when a pencil is inserted between the discs, andcombined resilient and magnetic means resisting separation of the discsand restoring the discs to normal position when a pencil is removed.

4. A pencil sharpener comprising a housing, a pair of motors enclosed bythe housing, a stator and rotor in each motor, a shaft for each rotor, apair of bearings in each motor in which the respective shafts and therotors carried thereby are journaled, and in which they arelongitudinally movable, said longitudinal movement of the shafts androtors being resisted by the magnetic field produced by the stators, anabrasive disc secured on the inner end of each rotor shaft, said discsbeing closely spaced but havingtheir adjacent faces beveled away fromeach other, with the greatest spacing between their peripheral edges, toform a tapering pencil point, and an opening formed in the housing topermit a'pencil to be inserted between the opposed beveled discs.

5. A pencil sharpener comprising a housing, a pair of motors enclosed bythe housing, a stator and rotor in each motor, a shaft for each rotor,a. pair of bearings in each motor in which the respective shafts and therotors carried thereby are journaled, and in which they arelongitudinally movable, a resilient end-thrust bearing adjacent theouter end of each rotor shaft to resist longitudinal movement of theshafts, an abrasive disc secured on the inner end of each shaft, saiddiscs being closely spaced but having their adjacent faces beveled awayfrom each other, with the greatest spacing between their peripheraledges, to form a tapering pencil point, and an opening formed in thehousing to permit a pencil to be inserted between the opposed beveleddiscs.

6. A pencil sharpener comprising a base plate, a pair of offsetbrackets, one adjacent each end of the base plate, an electric motorsupported by each offset bracket, a housing supported by the base andenclosing the motors, an end plate at each end of .the housing, boltsextending through the offset brackets, the motors and the end plates, tosecure the motors to the brackets and the end plates to the housing, ashaft in each motor, an abrasive disc secured on the inner end of eachshaft, said discs being closely spaced but having their adjacent facesbeveled away from each other to form a tapering pencil point, and anopening formed in the housing to permit a pencil to be inserted betweenthe opposed beveled faces of the discs.

'7. A pencil sharpener comprising a base plate, a pair of offsetbrackets, one adjacent each end of the base plate, an electric motorsupported by each offset bracket, a housing supported by the base andenclosing the motors, an end plate ateach end of the housing, boltsextending through the offset brackets, the motors and the end plates, tosecure the motors tothe brackets and the end plates to the housing, ashaft in each motor, an abrasive disc secured on the inner end of eachshaft, said discs being closely spaced but having their adjacent facesbeveled away from each other to'form a tapering pencil point, an openingformed in the housing to permit a pencil to be inserted between theopposed beveled faces of the discs, and a drawer insertable through anopening in the side of the housing, said drawer being supported by thebase between the offset brackets, and adapted to receive material groundoff pencils.

8. A pencil sharpener comprising a base plate,

apair of offset brackets, one adjacent each end of the base plate, anelectric motor supported by each offsetbracket, a housing supported bythe base and enclosing the motors, an end plate at each end of thehousing, bolts extending through the offset brackets, the motors and theend plates, to secure the motors to the brackets and the end plates tothe housing, a shaft in each motor, an abrasive disc secured on theinner end of each shaft, said discs being closely spaced but havingtheir adjacent faces beveled away from eachother to form a taperingpencil point, an opening formed in the housing to permit a pencil to beinserted between the opposed beveled faces of the discs, a drawerinsertable through an opening in the side ofthe housing, said drawerbeing supported by the base between the offset brackets, and adapted toreceive material ground oif pencils, I and a deflector disposedcentrally of the drawer and extending from end to end thereof,

to deflect the ground-off material into oppositesides of the drawer.

9. In a pencil sharpener of the character described a main housing, amotor housing enclosed by the main housing, said motor housing having arotor and a shaft and the rotor and shaft having a limited longitudinalmovement in the motor housing, an abrasive disc secured on the motorshaft, said disc having a beveled surface to engage and point the end ofa pencil, said disc, rotor and shaft moving longitudinally within themotor housing when pressure is exerted by a pencil against the beveledsurface of the disc, and magnetic means resisting longitudinal movementof the rotor, shaft and disc.

10. In a pencil sharpener of the character described a main housing, amotor housing enclosed by the main housing, said motor housing having arotor and a shaft and the rotor and shaft having a limited longitudinalmovement in the motor housing, an abrasive disc secured on the motorshaft, said disc having a beveled surface to engage and point the end ofa pencil, said disc, rotor and shaft moving longitudinally within themotor housing when pressure is exerted by a pencil against the beveledsurface of the disc, and combined resilient and magnetic means resistinglongitudinal movement of the rotor shaft and disc.

11. In a pencil sharpener of the character described a main housing, amotor housing enclosed by the main housing, said motor housing having a.rotor and a shaft and the rotor and shaft having a limited longitudinalmovement in the motor housing, an abrasive disc secured on one end ofthe motor shaft, said disc having a beveled surface to engage and pointthe end of a penciLsaid disc, rotor and shaft moving longitudinallywithin the motor housing when pressure is exerted by a pencil againstthe beveled surface of the disc, a resilient thrust bearing engaging theopposite end of the motor shaft to resist longitudinal movement, andmagnetic means to resist longitudinal movement.

EDGAR L. THEOBALD.

